From c4e072e8a58800f2dfd6c1e5e95009dd783061be Mon Sep 17 00:00:00 2001
From: jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Tue, 6 Feb 2007 00:10:32 +0000
Subject: Merged r4354:4390 from developer branch jcorgan/digital into trunk.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4391 221aa14e-8319-0410-a670-987f0aec2ac5
---
gnuradio-core/src/python/gnuradio/packet_utils.py | 31 +++++++++++++++--------
1 file changed, 20 insertions(+), 11 deletions(-)
(limited to 'gnuradio-core/src/python/gnuradio/packet_utils.py')
diff --git a/gnuradio-core/src/python/gnuradio/packet_utils.py b/gnuradio-core/src/python/gnuradio/packet_utils.py
index 59b1353662..182c80cdc8 100644
--- a/gnuradio-core/src/python/gnuradio/packet_utils.py
+++ b/gnuradio-core/src/python/gnuradio/packet_utils.py
@@ -86,22 +86,26 @@ def string_to_hex_list(s):
return map(lambda x: hex(ord(x)), s)
-def whiten(s):
+def whiten(s, o):
sa = Numeric.fromstring(s, Numeric.UnsignedInt8)
- z = sa ^ random_mask_vec8[0:len(sa)]
+ z = sa ^ random_mask_vec8[o:len(sa)+o]
return z.tostring()
-def dewhiten(s):
- return whiten(s) # self inverse
+def dewhiten(s, o):
+ return whiten(s, o) # self inverse
-def make_header(payload_len):
- return struct.pack('!HH', payload_len, payload_len)
+def make_header(payload_len, whitener_offset=0):
+ # Upper nibble is offset, lower 12 bits is len
+ val = ((whitener_offset & 0xf) << 12) | (payload_len & 0x0fff)
+ #print "offset =", whitener_offset, " len =", payload_len, " val=", val
+ return struct.pack('!HH', val, val)
def make_packet(payload, samples_per_symbol, bits_per_symbol,
- access_code=default_access_code, pad_for_usrp=True):
+ access_code=default_access_code, pad_for_usrp=True,
+ whitener_offset=0):
"""
- Build a packet, given access code and payload.
+ Build a packet, given access code, payload, and whitener offset
@param payload: packet payload, len [0, 4096]
@param samples_per_symbol: samples per symbol (needed for padding calculation)
@@ -109,6 +113,7 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol,
@param bits_per_symbol: (needed for padding calculation)
@type bits_per_symbol: int
@param access_code: string of ascii 0's and 1's
+ @param whitener_offset offset into whitener string to use [0-16)
Packet will have access code at the beginning, followed by length, payload
and finally CRC-32.
@@ -116,6 +121,9 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol,
if not is_1_0_string(access_code):
raise ValueError, "access_code must be a string containing only 0's and 1's (%r)" % (access_code,)
+ if not whitener_offset >=0 and whitener_offset < 16:
+ raise ValueError, "whitener_offset must be between 0 and 15, inclusive (%i)" % (whitener_offset,)
+
(packed_access_code, padded) = conv_1_0_string_to_packed_binary_string(access_code)
(packed_preamble, ignore) = conv_1_0_string_to_packed_binary_string(preamble)
@@ -127,7 +135,8 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol,
if L > MAXLEN:
raise ValueError, "len(payload) must be in [0, %d]" % (MAXLEN,)
- pkt = ''.join((packed_preamble, packed_access_code, make_header(L), whiten(payload_with_crc), '\x55'))
+ pkt = ''.join((packed_preamble, packed_access_code, make_header(L, whitener_offset),
+ whiten(payload_with_crc, whitener_offset), '\x55'))
if pad_for_usrp:
pkt = pkt + (_npadding_bytes(len(pkt), samples_per_symbol, bits_per_symbol) * '\x55')
@@ -156,13 +165,13 @@ def _npadding_bytes(pkt_byte_len, samples_per_symbol, bits_per_symbol):
return byte_modulus - r
-def unmake_packet(whitened_payload_with_crc):
+def unmake_packet(whitened_payload_with_crc, whitener_offset=0):
"""
Return (ok, payload)
@param whitened_payload_with_crc: string
"""
- payload_with_crc = dewhiten(whitened_payload_with_crc)
+ payload_with_crc = dewhiten(whitened_payload_with_crc, whitener_offset)
ok, payload = gru.check_crc32(payload_with_crc)
if 0:
--
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